If you have several different companies working on doing the same thing, they'll find different ways of doing it. This isn't necessarily a big deal for some things, like say a house. Having multiple contractors in one neighborhood works because the houses don't have to interact with each other. Your phone, on the other hand, is only useful to you if you can use it to communicate with other people, even if they're using a phone made by a different company. The same is true of the Internet -- if you want to access the whole thing, your computer needs to understand the language.
For WiFi networks, the Institute of Electrical and Electronics Engineers (IEEE) sets the standards. The IEEE's 802.11 rules set the framework that allows the wireless antenna in your computer to communicate with the wireless antenna in your router, which in turn sends the signal out of your house through a telephone or cable line. It doesn't make any difference what kind of information you're sending and receiving, as long as your computer speaks the same language as the server.
Networks of computers have become commonplace, and they're getting bigger -- from Local Area Networks (LANs) in your home or business, to Campus and Metropolitan Area Networks (CANs and MANs, respectively) as universities and cities have gotten into the act. The network by itself can be as simple as connecting two computers together, or accessing information from the university computers, but more often, they connect to the larger Internet, and wireless networks that allow computers to connect anywhere in range have become the norm.
Cell phone standards, however, evolved differently.